Question about when to contact ATC for clearance if avionics are turned on after engine start in the Bonanza

[toby23]

I just completed my first flight in the Turbo Bonanza and when I heard the sound change when the seals inflate - mind blown...

One thing I am unsure about, not being a real pilot, is when you would contact ATC for clearance if the avionics don't go on until after engine start (per checklist).

Thanks for any real world advice.
Toby

[SadBucket]

I generally ask after my run up irl. obviously I'd get taxi clearance to a place to runup if needed.

[toby23]

Thank you SadBucket. That sounds like the procedure at a small GA airport? What about at a larger airport? Would the avionics ever be turned on for clearance and then off again before engine start?